Magnetizer



Aug. 2, 1938. a. FREDRICKSON 2,125,628

MAGNETIZER- Original Filed Dec. 22, 1933 4 Sheets Sheet l I N 1 5 N TOR.

/-//.s HTTORNEK Aug; 2, 1938. G. FREDRICKSON I 2,125,628

MAGNETIZER Original Filedbec. 22, 1933 4 Sheets-Sheet 2 INVENTOR.

GUSTHV F/PEDR/CK-SO/Vj BY #15 HTTOR/VEX Aug. 2, 1938. G. FREDRICKSON 2,125,628

MAGNETIZER I Original Filed Dec. 22, 1933 4 Sheets-Sheet 5 INVENTOR' GUST/7 V FREDR/CKSON,

M5 WY 1938- G. FREIDRICKSON 2,125,628

- MAGNETIZER Original Filed Dec. 22, 1933 4 Sheets-Sheet 4 I N VE N TOR. GUS THV FFEDR/CKSON;

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BY M

Patented Aug. 2, 1938 UNITED STATES MAGNETIZER Gustav Fredrickson, Forestville, Conn., assignor,

by mesne assignments, to General Motors Corporation, Detroit, Mich, a corporation of Delaware Application December 22, 1933, Serial Ne. 703,595 Renewed September 18, 1935 14 Claims.

This invention relates to magnetizers and comprises all of the features of novelty herein disclosed. An object of the invention is to produce a magnetizer which is especially adapted for magnetizing ring-shaped articles or the like. Another object is to provide a readily portable magnetizer using an ordinary commercial direct current circuit, thus dispensing with expensive motor generator sets, converters, etc. Another object is to provide a magnetizer employing a surge generator which reverses its magnetic flux and so increases the amount of the magnetic charge imparted to the work. Another object is to produce a magnetizer having a toroidal work receptacle which is formed in separable sections to receive a ring to be magnetized. Still another object is to produce an improved method of magnetizing articles.

To these ends and also to improve generally upon devices of this character, the invention consists in the various matters hereinafter described and claimed. In its broader aspects, the invention is not necessarily limited to the speciflc construction selected for illustrative purposes in the accompanying drawings in which Fig. 1 is a front elevation of the apparatus.

Fig. 2 is a similar and enlarged view of'a portion of the apparatus, some parts being in section.

Fig. 3 is a sectional view of a portion of the cover. 1

Fig. 4 is a front view of a two-way switch.

Fig. 5 is a vertical sectional view on line 5-5 of Fig. 4.

Fig. 6 is a horizontal sectional view of parts oi. Fig. 5.

Fig. 7 is a front view of a switch.

Fig. 8 is a horizontal sectional view of parts of Fig. '7.

Fig. 9 is a planview of a detail.

Fig. 10 is a diagram.

A work-piece W, herein shown as a ring to be magnetized, is supported upon an insulating pad 2 engaging a circular plate 4 which is secured by screw bolts 8 to an insulating bench top 8. All of the mechanism to be described is supported by a suitable framework 10 having casters for ready portability. The plate 4 has a circular side wall I2 which is made springy by a series of slots I4. The upper inner portion of the side wall is provided with .an annular recess or shoulder leaving a thin upwardly projecting flange IS. The receptacle formedby the plate 4 and the side wall l2 has a cover plate l8 which is provided with a circular side wall 20 having slots 22 to make it-springy. Near the bottom, the side wall 20 has an exterior recess or shoulderleaving a downwardly projecting flange 24 arranged to yieldingly engage the flange i6 and thus make good electrical contact. 5

A suitable centering means or pilot is provided for the cover and this comprises a sleeve 28- arranged to surround the upper end of a core or plug 28. The sleeve is conveniently secured to the cover plate l8 as by welding (see Fig. 3) and 10 is slotted as indicated at 30 to make it springy. The core or plug 28 has a reduced portion carrying a set of insulating washers 32, the two outermost washers being largest and being clamped to the plate 4 by a nut 34. A pair of lifting bars 38 aresecured to the cover plate l8 and have flattened extensions connected by a handle 40. The bars are. slidable manually in bearings 42 in bosses 44 carried by bracket arms 46, and such sliding allows the cover to be shifted vertically into or out of electrical contact with the work receptacle. The centering sleeve 26 will engage the plug or core 28 before the flanges i6 and 24 enter one another, thus insuring a lineup of the flanges prior to actual contact.

In order to be able to insert the work in its receptacle, with the plug 28 inside the work, the cover is capable of swinging laterally out of the way and the swinging is also made use of to operate switches. The bracket arms 46 are mounted on an upright arm 48 which is pivoted by a pin .58 between lugs 52 on a bracket 54 which is bolted to the bench top 8. The arm 48 has one portion cut away for clearance in swinging and is provided with a stop plug 55 which engages the bracket 54 to position the cover in alignment with the receptacle. When the cover is swung to the left in Fig. 1 to its inoperative position, the arm 48 opens a spring-pressed switch as will later appear.

When the cover l8 slides up or down with the bars 38, its flange 24 operates a spring-pressed two-way switch by contact with a screw 60 which is adjustably secured by a lock nut 62 in a tapped opening of a slide rod 64. The rod 64 slides in a lug 68 carried by a switch housing 10 and is provided'with a collar 12 engaging a coil spring 14 which abuts against a guide bracket 16 on the switch housing. Upward movement of the rod is adjustably limited by a stop collar 18 fastened in adjusted position by a set screw 80 engaging aflat 82 on the rod. The rod has, at the rear, a vertically elongated notch having its end walls 84 straddling a pin 86 on a switch operating arm 88, the lost motion at the notch postponing the action of the switch until near the end of the movement of the rod in each direction. flanges I6 and 24 to make ample contact in the interval or to separate without arcing. The switch arm is secured to a rock shaft 90 journalled in a boss 92 of the switch housing. A spring clip 94 on a collar at the end of the shaft detachably supports a two-way switch 96- which is preferably a mercury switch as indicated. In the position indicated in Fig. 4, wires 98 and I00 have electrical connection through the mercury in two legs of the switch. When the rod 64 rises and tilts the switch clockwise,

wires I00 and I02 will be in electrical connection. To hold the switch arm in either of its two positions but not positively, thus to insure postponement of the movement of the switch arm until the lost motion of the rod 64 is taken up at the pin 06, aspring-pressed detcnt is provided. See Fig; 6.) This comprises a plate I04 secured to the switch housing and provided with a pair of shallow cavities I06 for co-operation with a ball I08 urged towards the cavities by a light coil spring H0. The spring abuts against a plug II2 threaded in a bushing II4 carried by the switch arm 08. The switch housing is closed at the front by a removable door II6 having locating lugs IIO to rest on the bottom of the 0 housing, spring clips I20 on the housing snapping over the, sides of the door.

As above stated, a spring-pressed switch is opened when the work receptacle cover I0 is swung over to the left in Fig. 2. The switch is preferably a one-way mercury switch and its operating means is similar to that for the twoway switch 96. A switch operating rod I22, (Figs. 2. '7 and 8), in the path of the swinging arm 48, is slidable in a bearing lug I24 on a switch houslu ing I26 and has a collar I20 abutting against a coil spring I30. The coil spring abuts against a guide bracket I32 and urges the rod upwardly to close the switch. Upward movement is adjustably limited by a stop collar I34 clamped in adjusted position on the rod by a set screw I36. The rod has a notch I38 receiving a pin I40 projecting from a switch arm I42 which is secured to a rock shaft I44 journalled in a boss of the switch housing I26. A spring clip I48 detachably 5 holds a mercuryswitch I50 to the rock shaft. A

detachable door which closes the rear of the housing is supported by lugs I52 and held closed by spring clips I54, these parts corresponding to those for the other switch housing. The switch 55 is moved to closed position by the spring I30 whenever the work-receptacle cover is closed over the work and the switch is opened when such cover is swung back.

Referring to Fig. 1, the portable bench frame 00 I0 has a bracket I56 supporting a box I50 con taining magnetic switches hereinafter referred to. The frame has a shelf I60 supporting a transformer I62 having a core which may be laminated or solid and a primary coil P of many turns in 65 series linking with a secondary coil S of two turns in parallel. Also on the shelf is a clip I64 supporting a plurality of ordinary tungsten filament lamps I66. The lamps have low resistance when cold and a high resistance when hot. One of the (0 terminals of the transformer secondary is connected by a lead wire I60.to a resistor or shunt I10 which has an electrical connection at I12 with the plate 4. An ammeter I14 is supported on the bench top and is connected to the shunt I10. The other terminal of the transformer is This provides a chance for the connected by a lead wire I16 to the lower end of the plug or core 20. The cover I0 acts like a switch in the secondary circuit of the transformer when the flanges 24 and I6 engage or disengage.

The electrical connections are shown diagrammatically in Fig. 10 wherein a main switch I10 connects the wiring system to a suitable source of power such as 110 volt, direct current. One of the line wires is connected by a branch wire I to terminals of electro-magnets I02 and I04, these magnets controlling magnetic switches I06 and I88 respectively. The magnetic switches have operating arms I90 interconnected by a link I92, the link having a lost-motion slot I94 engaged by a pin I96 on one of the arms. Thus both magnetic switches can be open at the same time but only one can close at a time and, whenever either is closed, the other is positively opened. Switch I86 has a pair of blades I98 and 200 to connect the power lines to the transformer primary, and switch I80 has a pair of blades 202 and 204 for the same purpose but one pair of blades directs the current through the transformer primary in a direction opposite to that of the other pair.

When a work-piece has been placed in the receptacle and the receptacle cover I8 is swung over towards closed position, the switch I50 closes by spring pressure and, as the cover slides down, such cover acts as a switch to first complete the secondary circuit and then as the cover reaches its lowest position, the two-way switch 96 is moved by the rod 64 to. that position wherein it electrically connects wires 96 and I00. Thus the magnet I02 is energized to close the magnetic switch I06 and open the magnetic switch I80. This action makes switch blades I98 and 200 effective to connect one power line to one terminal of the transformer primary and to connect the other power line to the bank of tungsten filament lamps I66, the latter being grouped in parallel and connected to the remaining terminal of the transformer primary. A surge of current from the transformer secondary through the core of the work-piece and around the latter magnetizes the piece. This magnetizing action is rendered doubly effective because of what occurs to the transformer core on a precedent lifting of the cover I0, as when removing a previously treated article. As the cover I8 rises, the surfaces at I6 and 24 separate and the secondary circuit of the transformer is broken. The rod 64 follows the cover upwardly .by spring pressure while the switch 96 is temporarily held by its detent but, as soon as the lost motion at the slot 04 is taken up, the switch 96 is thrown over by the force of the spring 14 and the wires I00 and I02 become electrically connected. This energizes the magnet I04, thereby closing the magnetic switch I08 and opening the magnetic switch Ill. Switch blades 202 and 204 become effective to connect the power lines to the transformer primary but the direction of current surge is opposite to that subsequently obtained when the cover is closed down over the article to be magneti'zed.

age surge is generated in the secondary. This work-piece.

direct current voltage surge is applied to a closed circuit through the work receptacle. The heavy direct current which flows through the work receptacle magnetizes the ring shaped work. The work receptacle is in effect a one-turn toroidal coil which can be opened to admit a ring shaped The work becomes a core within this one-turn toroidal coil when the work receptacle is closed on the work piece.

The magnetizer is workable without reversing the magnetic flux in the transformer during magnetizing of the work piece. The net change in magnetic flux in the core of the transformer. is limited in this case to the saturation flux in the transformer core. But by reversing the magnetic flux in the core of the transformer, the net change of magnetic flux is twice that obtained on re.- peated operations of magnetic flux in the transformer core in the same direction. The resulting currents built up through the work receptacle are about twice as great on complete reversal of transformer flux as on repetition of flux in the same direction.

The action may also be visualized as follows: The transformer core may be considered as initially in a neutral state magnetically with the north and south poles of its particles arranged helter-skelter. Upon the first surge of current, the particles have their north poles switched over to lie all in the same direction. The net or average change may be given a value of 90 or from zero to plus one. When the current is reversed, the particles are completely reversed through 180", a change from plus one to minus one or a diiierence of two. In eiiect, the work-piece is placed as a core in a toroidal coil and a heavy direct current caused to how through this toroidal coil of one turn. On being removed, the workpiece retains a permanent ring-shaped magnetic field useful for crack testing for instance.

When magnetizing a number of work-pieces in succession, the cover it? and its supporting arm d8 are moved. only enough to allow easy'insertion of the work in the receptacle. The repeated opening and closing of the cover throws the two-way switch 9G back and forth so that the magnets i532 and ltd are alternately energized to operate their corresponding switches. Thus'the current surges in the surge generator occur in opposite directions. When the last piece is magnetized, the cover is swung Way back and the arm d8 strikes the rod N22 to open the switch use so that both magnets are de-energized and both switches idii and 688 are open at the same time.

I claim:

1. in a device of the character described, a surge generator having a core, a primary coil, a secondary coil, means for causing a preliminary surge of current through the primary coil in one direction, means for thereafter establishing a magnetizing circuit extending through the opening in a ring shaped work-piece and around the entire circumference uniformly and including the secondary coil, and means ior causing a surge of current through the primary coil in the opposite direction; suhstantially as described.

2. In a device of the character described, a surge generator having a core, a primary coil, a secondary coil, means for causing a preliminary surge of current through the primary coil in one direction, a toroidal coil of one turn comprising a circumferentially. continuous wail adapted to contain a ring-shaped work-piece and a plug concentric with the wall and passing through the work-piece, the plug and the wall being connected to the secondary coil, and means for causing a surge of current through the primary coil in the opposite direction; substantially as described.

3. In a device of the character described, a surge generator having a core, a primarycoil, a secondary coil, means for causing a preliminary surge of current through the primary coil in one I direction, a toroidal coil formed in circumferentially continuous sections to open and receive a ring-shaped work-piece, means for bringing the sections into contact to put the toroidal coil in circuit with the secondary, and means for caus-' ing a surge of current through the primary coil in the opposite direction; substantially as described.

4. In a device of the character described, a surge generator having a core, a primary coil, and a secondary coil, a toroidal coil formed in circumferentially continuous sections to open and receive a ring-shaped work-piece, means for bringing the sections into contact to put the toroidal coil in circuit with the secondary, and

. means operated by movement of one of said sections for causing a surge of direct current through the primary coil to uniformly magnetize the work-piece contained in said sections; substantially as described.

5. In a device of the character described, a surge generator having a core, a primary coil, and a secondary coil, a toroidal coil formed in sections to open and receive a ring-shaped workpiece, means for bringing the sections into contact to put the toroidal coil in circuit with the secondary, and means operated by the movable section of the toroidal coil for completing a circult through the primary coil; substantially as described.

6. In a device of the character described, a

portable magnetizer comprising a frame, a surge generator having a primary coil, a secondary coil, and a core, a work receptacle for the work to be magnetized, means for placing the work receptacle in circuit with the secondary coil and, means automatically operated by said placing means for thereafter connecting the primary coil to a source of direct current; substantially as described.

"7. In a device of the character described, a portable magnetizer comprising a frame, a surge generator having a primary coil, a secondary coil, and a core, means for connecting the primary coil to a source of direct current, aworlr. receptacle adapted to open and close to place itself in and out of circuit with the secondary coil, and a switch operated by the opening and closing of the work receptacle for reversing the flow of current in the primary; substantially as described.

8. In a device of the character described, a work receptacle having a circumierentially continuous side wall of conducting material to surround a ring-like work-piece, and a core of conducting material concentric with the side wall to 'iii rial to completely surround the work-piece and a core of conducting material to enter the opening in the work-piece and form a toroidal coil of one turn around all portions of the work-piece, means for moving the cover into or out of electrical contact with the base portion and the core, and means external to the receptacle for causing a surge of magnetizing current through the toroidal coil; substantially as described.

10. In a device of the character described, a work receptacle comprising a base portion and a cover to contain a ring-like work-piece to be magnetized, the receptacle having a circumierentially continuous side wall of conducting material to completely surround the work-piece and a solid core of conducting material to enter the opening in the work-piece and form a toroidal coil of one turn around all portions of the work-piece, means for insulating the" core from the base portion, means for connecting the core and the base por tion to an external source of magnetizing current, and means connected to the cover for moving it into or out of electrical contact with the base portion and the core; substantially as described.

11. In a device of the character described, a work receptacle to contain a ring-like work-piece to be magnetized, the receptacle comprising a circumferentially continuous base portion and a circumferentially continuous cover of conducting material, a solid core of conducting material passing through the base portion and the opening of the work-piece, the core being insulated from the base portion, means for connecting the core and the base portion to an external source of magnetizing current, and means for electrically connecting the core and the base portion to the cover to complete the circuit in the receptacle and thereby magnetize the work-piece therein; substantially as described.

12. In a device of the character described, a

r scribed.

work receptacle to contain a ring-like work-piece to be magnetized, the receptacle comprising a base portion having a circumierentially continuous side wall of conducting material, a core entering the receptacle and the opening in the work-piece, a cover of conducting material having a rim to engage the side wall, guiding means between the core and the cover to center the cover with respect to the side wall, means connected to the cover for moving the cover towards the base portion to electrically connect the rim to the side wall, and means for connecting the core and the base portion to terminals of a magnetizing current; substantially as described.

13. The method of magnetizing a work-piece, which consists in causing a surge of direct current through a transformer primary in one direc tion, thereafter establishing a circuit from the secondary of the transformer through a conductor located in magnetizing relation to the workpiece, and causing a surge of direct current through the primary in the opposite direction while the piece remains in the same relation to the secondary; substantially as described.

14. The method of magnetizing a work-piece,

which consists in connecting the primary of a transformer to a source of direct current having high voltage and low current capacity, establishing a circuit from the secondary of the transformer through a conductor located in magnetizing relation to the work-piece, and reversing the direction of current flow in the primary to build up a high direct current surge of low voltage in the magnetizing circuit; substantially as de- GUSTAV FREDRICKSON.

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